Kumamoto International School (KIS) is a co-educational international school in Kumamoto City. Children can join at age two and stay through Grade 12 in one English-medium school. KIS began in 2003 as Picasso Preschool, with 15 children in a small rented building. The primary school opened in 2018, junior high in 2023 and the high school in 2025. Boarding followed in 2026.

KIS is an IB World School for the Primary Years Programme and the Diploma Programme, and a candidate school for the Middle Years Programme. The IB teaches students to think: to ask good questions, connect ideas and explain their reasoning. Cambridge runs alongside it and provides internationally benchmarked academic rigour, so students master the content too. Primary students (Grades 1–6) learn through inquiry, with English, mathematics, science and social studies built on a clear academic sequence. In junior high (Grades 7–10), students follow Cambridge Lower Secondary and then Cambridge IGCSE, and finish with the MYP Personal Project. Grades 11 and 12 take the IB Diploma.

English is the language of instruction. Japanese students study kokugo at native level, with full attention to kanji, reading and writing. Mandarin is taught by teachers from Taiwan in Traditional Chinese, from Grade 1 to the Diploma, where Language A is offered in English, Japanese and Chinese. Children do not need Japanese to enter. Those who arrive with little English get extra support until they can keep up in class.

Diploma students choose a science and technology route or a humanities route. Subjects include Physics, Chemistry, Biology, Mathematics, Business Management and Visual Arts, with Economics and Psychology available online. The Diploma opens doors overseas and in Japan, where 84 universities now admit students through IB routes, often on documents and interview rather than written exams. Many Japanese universities offer degree programmes taught entirely in English, and non-Japanese students can apply. A student does not need Japanese to study at KIS, or to go on to university in Japan. KIS provides college counselling for applications in Japan and overseas.

The school has more than 300 students from over 20 countries and more than 50 staff, with classes capped at 35 per grade. Its counsellors are licensed clinical psychologists who work in Japanese, English and Mandarin.

The boarding residence for Grades 10–12 is run with Kyoritsu Maintenance near Suizenji Station, with dorm parents living on site, controlled entry and security cameras. It serves students who live too far to commute, and students who stay at KIS when a parent is transferred away.

An expansion of the Toshima campus is due in December 2027. It adds larger science and art facilities, a cafeteria with an on-site kitchen, an athletic field, a dedicated exam room and more classrooms.

Clubs and after-school classes include basketball, volleyball, art, programming, abacus and Eiken preparation. The first Diploma class graduates in 2027.